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Stainless steel fasteners 101...
Hello. Lately i've come across a post:"...you can replace them with stainless rather than the cheesy monkey metal that some are made of these days. Don't replace caliper & suspension bolts with stainless unless it's A4 grade or better, it's hard but brittle & can snap under load."
I feel it is in all our interest to clarify the practicality of using SS fasteners. SS fasteners have a few good merrits: They are shiny and never rust, and i even have them on my bike. The practicality of these fasteners ends there. SS bolts have a low tensile strength equivilent to Gd.2 SAE, what someone might call monkey-metal http://www.horizonsunlimited.com/ubb/smile.gif For most situations this is fine, like anything threaded into aluminum or magnesium. Most likely the thread would strip before the bolt breaks. As someone mentioned before, never use these fasteners for stressed items, like brakes, suspension and sub-frames. These bolts, imho, should be a minimum Gr.8 SAE or Gr. 10.9 metric. Also, in the off-chance you might break one of these bolts, it's still possible to drill and use an easy-out. Try this with SS, there's a good chance the metal will work-harden, making it harder than the drillbit you are using http://www.horizonsunlimited.com/ubb/frown.gif SS fasteners come in two grades:A2 and A4. A2 stainless is #314stainless, used in regular aplications. A4 stainless is #316 stainless, used for salt-water (marine) aplications. Both grades are equivilent to Gr.2 SAE hardness, which is next to mild steel. Metric fasteners have their hardness grade stamped ot the head of the bolt eg. "8.8, 10.9, etc" SAE bolts have a number of slashes on the head. Count the slashes and add 2 eg." 6 slashes is a grade 8" Grade 5,8,10 SAE are equal to 8.8, 10.9, 12.9 metric respectively. I only use SS for its good looks and corrosion resistance. I've also broken enough to know what a pain in the ass they are to remove. Once they get hot enough, they become super hard and brittle. I hope this post helps the few of you who might be , well...screwed! Good luck! |
I recognise those words you've quoted at the start of your thread.
Agree completely, I've heard of stainless wheel spindles snapping & experienced first hand what happens when stainless work hardens, mainly on my small lathe when I'm being too gentle in the first place. Easy Outs, for me, are a last resort as they're also very brittle & just as big a pain as drilling stainless when they snap. The lesson for all of us, especially when using stainless bolts in to aluminium, is that in common with other areas of our lives, the correct lubrication is very important http://www.horizonsunlimited.com/ubb/rolleyes.gif Personally, I grease everything & use the right grease dependent on the fasteners location & application & as a result, never suffer seized bolts. I also try to avoid button head Allen/Torx bolts where any sort of torque is required. They simply don't have the depth to take the torque & simply round out, leading to more drilling/swearing/depression. [This message has been edited by Steve Pickford (edited 18 December 2004).] |
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Also thanks for the SS tip. I was just about to replace my Jeep’s winch mounting bolts with stainless steel ones since they showed signs of rust. I guess I will galvanize the old ones instead. ------------------ A.B. OasisPhoto.com – Images from the Magical Sahara. ShortWheelbase.com – Jeep preparations. Coordinates Converter – Lat/Long <-> UTM Conversion Tool. |
Sorry AB, I agree with Steve: lubricate almost all threads. I use MoS2 grease. Never had one come loose. There are exceptions, e.g. wheel bolts and nuts.
The worst are bolts in aluminium: If the thread is not lubed and gets damp you have an electric element and the corrosion can just about weld the bolt into place. I still remember with horror the XL500R years ago tha Honda in their infinite wisdom equipped with 7mm bolts in the rocker cover. The bolts were galvanised with a gold coloured metal. The bolts had often seized at the first service after 1000 km. Try finding 7mm thread inserts... ------------------ Salut from Southern France, the bikers' paradise, Peter. |
Hello. I use a product called Never-seize an all my fasteners, with the exception of any fastener which requires a critical torque reading eg:cylinder-heads. I use Never-seize al all external fasteners, especially wheel-lugs, never had a problem. For those of you who put SS nuts on SS bolts, ALWAYS!! use a lubricant. Even if it means rubbing the bolt behind your ear before assembly. Dry SS threads = DISASTER!
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Part of any vehicles servicing includes checking that bolts are tight - this is too ensure that they're not working loose. I'm also a great fan of Nyloc nuts. As I said, I lube everything, the lube depends on the application. I don't suffer seized bolts & I don't have parts falling off or stripped threads. |
I habitually use ccopper slip or copper grease as an anti seize agent especially when putting steel bolts into alu. Electrolitic corossion between disimilar metals ids what cuases most bolts to seize.
I I find that as I work on a bike I have bougt if I find lubricated threads I tend to find a bike that has been serviced and properly maintained. Its a habit you get into like using a torque wrench. Charlie |
Just a comment.. Stainless and aluminium is a bether mix than ordinary stell and alu. I know this after several years work on aluminium boats. But do grease the bolts, or lock them whit f.x. Loctite and use some lube when you unsrew(?) them.
Happy new year |
While looking for some blue Loctite in my local auto-parts store I came across what I assume to be a new Loctite - designed to lube steel/SS bolts going into aluminium threads. I guess this was developed for alu heads on cars.
Being a sucker I bought some, haven't used it yet tho. ------------------ Barry 3AJ Tenere |
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